| abstract |
Disclosed is a compound represented by the formula (1) or a salt thereof, which has an affinity to amyloid, shows a satisfactorily rapid clearance from a normal tissue and is reduced in toxicity such as mutagenicity. Also disclosed is a low-toxic diagnostic agent for Alzheimer's disease comprising the compound. (1) [wherein A1, A2, A3 and A4 independently represent a carbon or a nitrogen; and R3 represents a group represented by the formula: (wherein R1 represents a radioactive halogen substituent; m represents an integer of 0 to 4; and n represents an integer of 0 or 1) provided that at least one of A1, A2, A3 and A4 represents a carbon and R3 is bound to the carbon A1, A2, A3 or A4]. |